// Copyright 2014 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#if V8_TARGET_ARCH_PPC

#include "src/regexp/ppc/regexp-macro-assembler-ppc.h"

#include "src/assembler-inl.h"
#include "src/base/bits.h"
#include "src/log.h"
#include "src/macro-assembler.h"
#include "src/regexp/regexp-macro-assembler.h"
#include "src/regexp/regexp-stack.h"
#include "src/snapshot/embedded-data.h"
#include "src/unicode.h"

namespace v8 {
namespace internal {

    /*
 * This assembler uses the following register assignment convention
 * - r25: Temporarily stores the index of capture start after a matching pass
 *        for a global regexp.
 * - r26: Pointer to current Code object including heap object tag.
 * - r27: Current position in input, as negative offset from end of string.
 *        Please notice that this is the byte offset, not the character offset!
 * - r28: Currently loaded character. Must be loaded using
 *        LoadCurrentCharacter before using any of the dispatch methods.
 * - r29: Points to tip of backtrack stack
 * - r30: End of input (points to byte after last character in input).
 * - r31: Frame pointer. Used to access arguments, local variables and
 *         RegExp registers.
 * - r12: IP register, used by assembler. Very volatile.
 * - r1/sp : Points to tip of C stack.
 *
 * The remaining registers are free for computations.
 * Each call to a public method should retain this convention.
 *
 * The stack will have the following structure:
 *  - fp[40]  Isolate* isolate   (address of the current isolate)
 *  - fp[36]  lr save area (currently unused)
 *  - fp[32]  backchain    (currently unused)
 *  --- sp when called ---
 *  - fp[28]  return address     (lr).
 *  - fp[24]  old frame pointer  (r31).
 *  - fp[0..20]  backup of registers r25..r30
 *  --- frame pointer ----
 *  - fp[-4]  direct_call        (if 1, direct call from JavaScript code,
 *                                if 0, call through the runtime system).
 *  - fp[-8]  stack_area_base    (high end of the memory area to use as
 *                                backtracking stack).
 *  - fp[-12] capture array size (may fit multiple sets of matches)
 *  - fp[-16] int* capture_array (int[num_saved_registers_], for output).
 *  - fp[-20] end of input       (address of end of string).
 *  - fp[-24] start of input     (address of first character in string).
 *  - fp[-28] start index        (character index of start).
 *  - fp[-32] void* input_string (location of a handle containing the string).
 *  - fp[-36] success counter    (only for global regexps to count matches).
 *  - fp[-40] Offset of location before start of input (effectively character
 *            string start - 1). Used to initialize capture registers to a
 *            non-position.
 *  - fp[-44] At start (if 1, we are starting at the start of the
 *    string, otherwise 0)
 *  - fp[-48] register 0         (Only positions must be stored in the first
 *  -         register 1          num_saved_registers_ registers)
 *  -         ...
 *  -         register num_registers-1
 *  --- sp ---
 *
 * The first num_saved_registers_ registers are initialized to point to
 * "character -1" in the string (i.e., char_size() bytes before the first
 * character of the string). The remaining registers start out as garbage.
 *
 * The data up to the return address must be placed there by the calling
 * code and the remaining arguments are passed in registers, e.g. by calling the
 * code entry as cast to a function with the signature:
 * int (*match)(String input_string,
 *              int start_index,
 *              Address start,
 *              Address end,
 *              int* capture_output_array,
 *              int num_capture_registers,
 *              byte* stack_area_base,
 *              bool direct_call = false,
 *              Isolate* isolate);
 * The call is performed by NativeRegExpMacroAssembler::Execute()
 * (in regexp-macro-assembler.cc) via the GeneratedCode wrapper.
 */

#define __ ACCESS_MASM(masm_)

    const int RegExpMacroAssemblerPPC::kRegExpCodeSize;

    RegExpMacroAssemblerPPC::RegExpMacroAssemblerPPC(Isolate* isolate, Zone* zone,
        Mode mode,
        int registers_to_save)
        : NativeRegExpMacroAssembler(isolate, zone)
        , masm_(new MacroAssembler(isolate, CodeObjectRequired::kYes,
              NewAssemblerBuffer(kRegExpCodeSize)))
        , mode_(mode)
        , num_registers_(registers_to_save)
        , num_saved_registers_(registers_to_save)
        , entry_label_()
        , start_label_()
        , success_label_()
        , backtrack_label_()
        , exit_label_()
        , internal_failure_label_()
    {
        DCHECK_EQ(0, registers_to_save % 2);

        // Because RegExp code respects C ABI, so needs a FD
        __ function_descriptor();

        __ b(&entry_label_); // We'll write the entry code later.
        // If the code gets too big or corrupted, an internal exception will be
        // raised, and we will exit right away.
        __ bind(&internal_failure_label_);
        __ li(r3, Operand(FAILURE));
        __ Ret();
        __ bind(&start_label_); // And then continue from here.
    }

    RegExpMacroAssemblerPPC::~RegExpMacroAssemblerPPC()
    {
        delete masm_;
        // Unuse labels in case we throw away the assembler without calling GetCode.
        entry_label_.Unuse();
        start_label_.Unuse();
        success_label_.Unuse();
        backtrack_label_.Unuse();
        exit_label_.Unuse();
        check_preempt_label_.Unuse();
        stack_overflow_label_.Unuse();
        internal_failure_label_.Unuse();
    }

    int RegExpMacroAssemblerPPC::stack_limit_slack()
    {
        return RegExpStack::kStackLimitSlack;
    }

    void RegExpMacroAssemblerPPC::AdvanceCurrentPosition(int by)
    {
        if (by != 0) {
            if (is_int16(by * char_size())) {
                __ addi(current_input_offset(), current_input_offset(),
                    Operand(by * char_size()));
            } else {
                __ mov(r0, Operand(by * char_size()));
                __ add(current_input_offset(), r0, current_input_offset());
            }
        }
    }

    void RegExpMacroAssemblerPPC::AdvanceRegister(int reg, int by)
    {
        DCHECK_LE(0, reg);
        DCHECK_GT(num_registers_, reg);
        if (by != 0) {
            __ LoadP(r3, register_location(reg), r0);
            __ mov(r0, Operand(by));
            __ add(r3, r3, r0);
            __ StoreP(r3, register_location(reg), r0);
        }
    }

    void RegExpMacroAssemblerPPC::Backtrack()
    {
        CheckPreemption();
        // Pop Code offset from backtrack stack, add Code and jump to location.
        Pop(r3);
        __ add(r3, r3, code_pointer());
        __ Jump(r3);
    }

    void RegExpMacroAssemblerPPC::Bind(Label* label) { __ bind(label); }

    void RegExpMacroAssemblerPPC::CheckCharacter(uint32_t c, Label* on_equal)
    {
        __ Cmpli(current_character(), Operand(c), r0);
        BranchOrBacktrack(eq, on_equal);
    }

    void RegExpMacroAssemblerPPC::CheckCharacterGT(uc16 limit, Label* on_greater)
    {
        __ Cmpli(current_character(), Operand(limit), r0);
        BranchOrBacktrack(gt, on_greater);
    }

    void RegExpMacroAssemblerPPC::CheckAtStart(Label* on_at_start)
    {
        __ LoadP(r4, MemOperand(frame_pointer(), kStringStartMinusOne));
        __ addi(r3, current_input_offset(), Operand(-char_size()));
        __ cmp(r3, r4);
        BranchOrBacktrack(eq, on_at_start);
    }

    void RegExpMacroAssemblerPPC::CheckNotAtStart(int cp_offset,
        Label* on_not_at_start)
    {
        __ LoadP(r4, MemOperand(frame_pointer(), kStringStartMinusOne));
        __ addi(r3, current_input_offset(),
            Operand(-char_size() + cp_offset * char_size()));
        __ cmp(r3, r4);
        BranchOrBacktrack(ne, on_not_at_start);
    }

    void RegExpMacroAssemblerPPC::CheckCharacterLT(uc16 limit, Label* on_less)
    {
        __ Cmpli(current_character(), Operand(limit), r0);
        BranchOrBacktrack(lt, on_less);
    }

    void RegExpMacroAssemblerPPC::CheckGreedyLoop(Label* on_equal)
    {
        Label backtrack_non_equal;
        __ LoadP(r3, MemOperand(backtrack_stackpointer(), 0));
        __ cmp(current_input_offset(), r3);
        __ bne(&backtrack_non_equal);
        __ addi(backtrack_stackpointer(), backtrack_stackpointer(),
            Operand(kPointerSize));

        __ bind(&backtrack_non_equal);
        BranchOrBacktrack(eq, on_equal);
    }

    void RegExpMacroAssemblerPPC::CheckNotBackReferenceIgnoreCase(
        int start_reg, bool read_backward, bool unicode, Label* on_no_match)
    {
        Label fallthrough;
        __ LoadP(r3, register_location(start_reg), r0); // Index of start of capture
        __ LoadP(r4, register_location(start_reg + 1), r0); // Index of end
        __ sub(r4, r4, r3, LeaveOE, SetRC); // Length of capture.

        // At this point, the capture registers are either both set or both cleared.
        // If the capture length is zero, then the capture is either empty or cleared.
        // Fall through in both cases.
        __ beq(&fallthrough, cr0);

        // Check that there are enough characters left in the input.
        if (read_backward) {
            __ LoadP(r6, MemOperand(frame_pointer(), kStringStartMinusOne));
            __ add(r6, r6, r4);
            __ cmp(current_input_offset(), r6);
            BranchOrBacktrack(le, on_no_match);
        } else {
            __ add(r0, r4, current_input_offset(), LeaveOE, SetRC);
            BranchOrBacktrack(gt, on_no_match, cr0);
        }

        if (mode_ == LATIN1) {
            Label success;
            Label fail;
            Label loop_check;

            // r3 - offset of start of capture
            // r4 - length of capture
            __ add(r3, r3, end_of_input_address());
            __ add(r5, end_of_input_address(), current_input_offset());
            if (read_backward) {
                __ sub(r5, r5, r4); // Offset by length when matching backwards.
            }
            __ add(r4, r3, r4);

            // r3 - Address of start of capture.
            // r4 - Address of end of capture
            // r5 - Address of current input position.

            Label loop;
            __ bind(&loop);
            __ lbz(r6, MemOperand(r3));
            __ addi(r3, r3, Operand(char_size()));
            __ lbz(r25, MemOperand(r5));
            __ addi(r5, r5, Operand(char_size()));
            __ cmp(r25, r6);
            __ beq(&loop_check);

            // Mismatch, try case-insensitive match (converting letters to lower-case).
            __ ori(r6, r6, Operand(0x20)); // Convert capture character to lower-case.
            __ ori(r25, r25, Operand(0x20)); // Also convert input character.
            __ cmp(r25, r6);
            __ bne(&fail);
            __ subi(r6, r6, Operand('a'));
            __ cmpli(r6, Operand('z' - 'a')); // Is r6 a lowercase letter?
            __ ble(&loop_check); // In range 'a'-'z'.
            // Latin-1: Check for values in range [224,254] but not 247.
            __ subi(r6, r6, Operand(224 - 'a'));
            __ cmpli(r6, Operand(254 - 224));
            __ bgt(&fail); // Weren't Latin-1 letters.
            __ cmpi(r6, Operand(247 - 224)); // Check for 247.
            __ beq(&fail);

            __ bind(&loop_check);
            __ cmp(r3, r4);
            __ blt(&loop);
            __ b(&success);

            __ bind(&fail);
            BranchOrBacktrack(al, on_no_match);

            __ bind(&success);
            // Compute new value of character position after the matched part.
            __ sub(current_input_offset(), r5, end_of_input_address());
            if (read_backward) {
                __ LoadP(r3, register_location(start_reg)); // Index of start of capture
                __ LoadP(r4,
                    register_location(start_reg + 1)); // Index of end of capture
                __ add(current_input_offset(), current_input_offset(), r3);
                __ sub(current_input_offset(), current_input_offset(), r4);
            }
        } else {
            DCHECK(mode_ == UC16);
            int argument_count = 4;
            __ PrepareCallCFunction(argument_count, r5);

            // r3 - offset of start of capture
            // r4 - length of capture

            // Put arguments into arguments registers.
            // Parameters are
            //   r3: Address byte_offset1 - Address captured substring's start.
            //   r4: Address byte_offset2 - Address of current character position.
            //   r5: size_t byte_length - length of capture in bytes(!)
            //   r6: Isolate* isolate or 0 if unicode flag.

            // Address of start of capture.
            __ add(r3, r3, end_of_input_address());
            // Length of capture.
            __ mr(r5, r4);
            // Save length in callee-save register for use on return.
            __ mr(r25, r4);
            // Address of current input position.
            __ add(r4, current_input_offset(), end_of_input_address());
            if (read_backward) {
                __ sub(r4, r4, r25);
            }
            // Isolate.
#ifdef V8_INTL_SUPPORT
            if (unicode) {
                __ li(r6, Operand::Zero());
            } else // NOLINT
#endif // V8_INTL_SUPPORT
            {
                __ mov(r6, Operand(ExternalReference::isolate_address(isolate())));
            }

            {
                AllowExternalCallThatCantCauseGC scope(masm_);
                ExternalReference function = ExternalReference::re_case_insensitive_compare_uc16(isolate());
                __ CallCFunction(function, argument_count);
            }

            // Check if function returned non-zero for success or zero for failure.
            __ cmpi(r3, Operand::Zero());
            BranchOrBacktrack(eq, on_no_match);

            // On success, advance position by length of capture.
            if (read_backward) {
                __ sub(current_input_offset(), current_input_offset(), r25);
            } else {
                __ add(current_input_offset(), current_input_offset(), r25);
            }
        }

        __ bind(&fallthrough);
    }

    void RegExpMacroAssemblerPPC::CheckNotBackReference(int start_reg,
        bool read_backward,
        Label* on_no_match)
    {
        Label fallthrough;

        // Find length of back-referenced capture.
        __ LoadP(r3, register_location(start_reg), r0);
        __ LoadP(r4, register_location(start_reg + 1), r0);
        __ sub(r4, r4, r3, LeaveOE, SetRC); // Length to check.

        // At this point, the capture registers are either both set or both cleared.
        // If the capture length is zero, then the capture is either empty or cleared.
        // Fall through in both cases.
        __ beq(&fallthrough, cr0);

        // Check that there are enough characters left in the input.
        if (read_backward) {
            __ LoadP(r6, MemOperand(frame_pointer(), kStringStartMinusOne));
            __ add(r6, r6, r4);
            __ cmp(current_input_offset(), r6);
            BranchOrBacktrack(le, on_no_match);
        } else {
            __ add(r0, r4, current_input_offset(), LeaveOE, SetRC);
            BranchOrBacktrack(gt, on_no_match, cr0);
        }

        // r3 - offset of start of capture
        // r4 - length of capture
        __ add(r3, r3, end_of_input_address());
        __ add(r5, end_of_input_address(), current_input_offset());
        if (read_backward) {
            __ sub(r5, r5, r4); // Offset by length when matching backwards.
        }
        __ add(r4, r4, r3);

        Label loop;
        __ bind(&loop);
        if (mode_ == LATIN1) {
            __ lbz(r6, MemOperand(r3));
            __ addi(r3, r3, Operand(char_size()));
            __ lbz(r25, MemOperand(r5));
            __ addi(r5, r5, Operand(char_size()));
        } else {
            DCHECK(mode_ == UC16);
            __ lhz(r6, MemOperand(r3));
            __ addi(r3, r3, Operand(char_size()));
            __ lhz(r25, MemOperand(r5));
            __ addi(r5, r5, Operand(char_size()));
        }
        __ cmp(r6, r25);
        BranchOrBacktrack(ne, on_no_match);
        __ cmp(r3, r4);
        __ blt(&loop);

        // Move current character position to position after match.
        __ sub(current_input_offset(), r5, end_of_input_address());
        if (read_backward) {
            __ LoadP(r3, register_location(start_reg)); // Index of start of capture
            __ LoadP(r4, register_location(start_reg + 1)); // Index of end of capture
            __ add(current_input_offset(), current_input_offset(), r3);
            __ sub(current_input_offset(), current_input_offset(), r4);
        }

        __ bind(&fallthrough);
    }

    void RegExpMacroAssemblerPPC::CheckNotCharacter(unsigned c,
        Label* on_not_equal)
    {
        __ Cmpli(current_character(), Operand(c), r0);
        BranchOrBacktrack(ne, on_not_equal);
    }

    void RegExpMacroAssemblerPPC::CheckCharacterAfterAnd(uint32_t c, uint32_t mask,
        Label* on_equal)
    {
        __ mov(r0, Operand(mask));
        if (c == 0) {
            __ and_(r3, current_character(), r0, SetRC);
        } else {
            __ and_(r3, current_character(), r0);
            __ Cmpli(r3, Operand(c), r0, cr0);
        }
        BranchOrBacktrack(eq, on_equal, cr0);
    }

    void RegExpMacroAssemblerPPC::CheckNotCharacterAfterAnd(unsigned c,
        unsigned mask,
        Label* on_not_equal)
    {
        __ mov(r0, Operand(mask));
        if (c == 0) {
            __ and_(r3, current_character(), r0, SetRC);
        } else {
            __ and_(r3, current_character(), r0);
            __ Cmpli(r3, Operand(c), r0, cr0);
        }
        BranchOrBacktrack(ne, on_not_equal, cr0);
    }

    void RegExpMacroAssemblerPPC::CheckNotCharacterAfterMinusAnd(
        uc16 c, uc16 minus, uc16 mask, Label* on_not_equal)
    {
        DCHECK_GT(String::kMaxUtf16CodeUnit, minus);
        __ subi(r3, current_character(), Operand(minus));
        __ mov(r0, Operand(mask));
        __ and_(r3, r3, r0);
        __ Cmpli(r3, Operand(c), r0);
        BranchOrBacktrack(ne, on_not_equal);
    }

    void RegExpMacroAssemblerPPC::CheckCharacterInRange(uc16 from, uc16 to,
        Label* on_in_range)
    {
        __ mov(r0, Operand(from));
        __ sub(r3, current_character(), r0);
        __ Cmpli(r3, Operand(to - from), r0);
        BranchOrBacktrack(le, on_in_range); // Unsigned lower-or-same condition.
    }

    void RegExpMacroAssemblerPPC::CheckCharacterNotInRange(uc16 from, uc16 to,
        Label* on_not_in_range)
    {
        __ mov(r0, Operand(from));
        __ sub(r3, current_character(), r0);
        __ Cmpli(r3, Operand(to - from), r0);
        BranchOrBacktrack(gt, on_not_in_range); // Unsigned higher condition.
    }

    void RegExpMacroAssemblerPPC::CheckBitInTable(Handle<ByteArray> table,
        Label* on_bit_set)
    {
        __ mov(r3, Operand(table));
        if (mode_ != LATIN1 || kTableMask != String::kMaxOneByteCharCode) {
            __ andi(r4, current_character(), Operand(kTableSize - 1));
            __ addi(r4, r4, Operand(ByteArray::kHeaderSize - kHeapObjectTag));
        } else {
            __ addi(r4, current_character(),
                Operand(ByteArray::kHeaderSize - kHeapObjectTag));
        }
        __ lbzx(r3, MemOperand(r3, r4));
        __ cmpi(r3, Operand::Zero());
        BranchOrBacktrack(ne, on_bit_set);
    }

    bool RegExpMacroAssemblerPPC::CheckSpecialCharacterClass(uc16 type,
        Label* on_no_match)
    {
        // Range checks (c in min..max) are generally implemented by an unsigned
        // (c - min) <= (max - min) check
        switch (type) {
        case 's':
            // Match space-characters
            if (mode_ == LATIN1) {
                // One byte space characters are '\t'..'\r', ' ' and \u00a0.
                Label success;
                __ cmpi(current_character(), Operand(' '));
                __ beq(&success);
                // Check range 0x09..0x0D
                __ subi(r3, current_character(), Operand('\t'));
                __ cmpli(r3, Operand('\r' - '\t'));
                __ ble(&success);
                // \u00a0 (NBSP).
                __ cmpi(r3, Operand(0x00A0 - '\t'));
                BranchOrBacktrack(ne, on_no_match);
                __ bind(&success);
                return true;
            }
            return false;
        case 'S':
            // The emitted code for generic character classes is good enough.
            return false;
        case 'd':
            // Match ASCII digits ('0'..'9')
            __ subi(r3, current_character(), Operand('0'));
            __ cmpli(r3, Operand('9' - '0'));
            BranchOrBacktrack(gt, on_no_match);
            return true;
        case 'D':
            // Match non ASCII-digits
            __ subi(r3, current_character(), Operand('0'));
            __ cmpli(r3, Operand('9' - '0'));
            BranchOrBacktrack(le, on_no_match);
            return true;
        case '.': {
            // Match non-newlines (not 0x0A('\n'), 0x0D('\r'), 0x2028 and 0x2029)
            __ xori(r3, current_character(), Operand(0x01));
            // See if current character is '\n'^1 or '\r'^1, i.e., 0x0B or 0x0C
            __ subi(r3, r3, Operand(0x0B));
            __ cmpli(r3, Operand(0x0C - 0x0B));
            BranchOrBacktrack(le, on_no_match);
            if (mode_ == UC16) {
                // Compare original value to 0x2028 and 0x2029, using the already
                // computed (current_char ^ 0x01 - 0x0B). I.e., check for
                // 0x201D (0x2028 - 0x0B) or 0x201E.
                __ subi(r3, r3, Operand(0x2028 - 0x0B));
                __ cmpli(r3, Operand(1));
                BranchOrBacktrack(le, on_no_match);
            }
            return true;
        }
        case 'n': {
            // Match newlines (0x0A('\n'), 0x0D('\r'), 0x2028 and 0x2029)
            __ xori(r3, current_character(), Operand(0x01));
            // See if current character is '\n'^1 or '\r'^1, i.e., 0x0B or 0x0C
            __ subi(r3, r3, Operand(0x0B));
            __ cmpli(r3, Operand(0x0C - 0x0B));
            if (mode_ == LATIN1) {
                BranchOrBacktrack(gt, on_no_match);
            } else {
                Label done;
                __ ble(&done);
                // Compare original value to 0x2028 and 0x2029, using the already
                // computed (current_char ^ 0x01 - 0x0B). I.e., check for
                // 0x201D (0x2028 - 0x0B) or 0x201E.
                __ subi(r3, r3, Operand(0x2028 - 0x0B));
                __ cmpli(r3, Operand(1));
                BranchOrBacktrack(gt, on_no_match);
                __ bind(&done);
            }
            return true;
        }
        case 'w': {
            if (mode_ != LATIN1) {
                // Table is 256 entries, so all Latin1 characters can be tested.
                __ cmpi(current_character(), Operand('z'));
                BranchOrBacktrack(gt, on_no_match);
            }
            ExternalReference map = ExternalReference::re_word_character_map(isolate());
            __ mov(r3, Operand(map));
            __ lbzx(r3, MemOperand(r3, current_character()));
            __ cmpli(r3, Operand::Zero());
            BranchOrBacktrack(eq, on_no_match);
            return true;
        }
        case 'W': {
            Label done;
            if (mode_ != LATIN1) {
                // Table is 256 entries, so all Latin1 characters can be tested.
                __ cmpli(current_character(), Operand('z'));
                __ bgt(&done);
            }
            ExternalReference map = ExternalReference::re_word_character_map(isolate());
            __ mov(r3, Operand(map));
            __ lbzx(r3, MemOperand(r3, current_character()));
            __ cmpli(r3, Operand::Zero());
            BranchOrBacktrack(ne, on_no_match);
            if (mode_ != LATIN1) {
                __ bind(&done);
            }
            return true;
        }
        case '*':
            // Match any character.
            return true;
        // No custom implementation (yet): s(UC16), S(UC16).
        default:
            return false;
        }
    }

    void RegExpMacroAssemblerPPC::Fail()
    {
        __ li(r3, Operand(FAILURE));
        __ b(&exit_label_);
    }

    Handle<HeapObject> RegExpMacroAssemblerPPC::GetCode(Handle<String> source)
    {
        Label return_r3;

        if (masm_->has_exception()) {
            // If the code gets corrupted due to long regular expressions and lack of
            // space on trampolines, an internal exception flag is set. If this case
            // is detected, we will jump into exit sequence right away.
            __ bind_to(&entry_label_, internal_failure_label_.pos());
        } else {
            // Finalize code - write the entry point code now we know how many
            // registers we need.

            // Entry code:
            __ bind(&entry_label_);

            // Tell the system that we have a stack frame.  Because the type
            // is MANUAL, no is generated.
            FrameScope scope(masm_, StackFrame::MANUAL);

            // Ensure register assigments are consistent with callee save mask
            DCHECK(r25.bit() & kRegExpCalleeSaved);
            DCHECK(code_pointer().bit() & kRegExpCalleeSaved);
            DCHECK(current_input_offset().bit() & kRegExpCalleeSaved);
            DCHECK(current_character().bit() & kRegExpCalleeSaved);
            DCHECK(backtrack_stackpointer().bit() & kRegExpCalleeSaved);
            DCHECK(end_of_input_address().bit() & kRegExpCalleeSaved);
            DCHECK(frame_pointer().bit() & kRegExpCalleeSaved);

            // Actually emit code to start a new stack frame.
            // Push arguments
            // Save callee-save registers.
            // Start new stack frame.
            // Store link register in existing stack-cell.
            // Order here should correspond to order of offset constants in header file.
            RegList registers_to_retain = kRegExpCalleeSaved;
            RegList argument_registers = r3.bit() | r4.bit() | r5.bit() | r6.bit() | r7.bit() | r8.bit() | r9.bit() | r10.bit();
            __ mflr(r0);
            __ push(r0);
            __ MultiPush(argument_registers | registers_to_retain);
            // Set frame pointer in space for it if this is not a direct call
            // from generated code.
            __ addi(frame_pointer(), sp, Operand(8 * kPointerSize));
            __ li(r3, Operand::Zero());
            __ push(r3); // Make room for success counter and initialize it to 0.
            __ push(r3); // Make room for "string start - 1" constant.
            // Check if we have space on the stack for registers.
            Label stack_limit_hit;
            Label stack_ok;

            ExternalReference stack_limit = ExternalReference::address_of_stack_limit(isolate());
            __ mov(r3, Operand(stack_limit));
            __ LoadP(r3, MemOperand(r3));
            __ sub(r3, sp, r3, LeaveOE, SetRC);
            // Handle it if the stack pointer is already below the stack limit.
            __ ble(&stack_limit_hit, cr0);
            // Check if there is room for the variable number of registers above
            // the stack limit.
            __ Cmpli(r3, Operand(num_registers_ * kPointerSize), r0);
            __ bge(&stack_ok);
            // Exit with OutOfMemory exception. There is not enough space on the stack
            // for our working registers.
            __ li(r3, Operand(EXCEPTION));
            __ b(&return_r3);

            __ bind(&stack_limit_hit);
            CallCheckStackGuardState(r3);
            __ cmpi(r3, Operand::Zero());
            // If returned value is non-zero, we exit with the returned value as result.
            __ bne(&return_r3);

            __ bind(&stack_ok);

            // Allocate space on stack for registers.
            __ Add(sp, sp, -num_registers_ * kPointerSize, r0);
            // Load string end.
            __ LoadP(end_of_input_address(), MemOperand(frame_pointer(), kInputEnd));
            // Load input start.
            __ LoadP(r3, MemOperand(frame_pointer(), kInputStart));
            // Find negative length (offset of start relative to end).
            __ sub(current_input_offset(), r3, end_of_input_address());
            // Set r3 to address of char before start of the input string
            // (effectively string position -1).
            __ LoadP(r4, MemOperand(frame_pointer(), kStartIndex));
            __ subi(r3, current_input_offset(), Operand(char_size()));
            if (mode_ == UC16) {
                __ ShiftLeftImm(r0, r4, Operand(1));
                __ sub(r3, r3, r0);
            } else {
                __ sub(r3, r3, r4);
            }
            // Store this value in a local variable, for use when clearing
            // position registers.
            __ StoreP(r3, MemOperand(frame_pointer(), kStringStartMinusOne));

            // Initialize code pointer register
            __ mov(code_pointer(), Operand(masm_->CodeObject()));

            Label load_char_start_regexp, start_regexp;
            // Load newline if index is at start, previous character otherwise.
            __ cmpi(r4, Operand::Zero());
            __ bne(&load_char_start_regexp);
            __ li(current_character(), Operand('\n'));
            __ b(&start_regexp);

            // Global regexp restarts matching here.
            __ bind(&load_char_start_regexp);
            // Load previous char as initial value of current character register.
            LoadCurrentCharacterUnchecked(-1, 1);
            __ bind(&start_regexp);

            // Initialize on-stack registers.
            if (num_saved_registers_ > 0) { // Always is, if generated from a regexp.
                // Fill saved registers with initial value = start offset - 1
                if (num_saved_registers_ > 8) {
                    // One slot beyond address of register 0.
                    __ addi(r4, frame_pointer(), Operand(kRegisterZero + kPointerSize));
                    __ li(r5, Operand(num_saved_registers_));
                    __ mtctr(r5);
                    Label init_loop;
                    __ bind(&init_loop);
                    __ StorePU(r3, MemOperand(r4, -kPointerSize));
                    __ bdnz(&init_loop);
                } else {
                    for (int i = 0; i < num_saved_registers_; i++) {
                        __ StoreP(r3, register_location(i), r0);
                    }
                }
            }

            // Initialize backtrack stack pointer.
            __ LoadP(backtrack_stackpointer(),
                MemOperand(frame_pointer(), kStackHighEnd));

            __ b(&start_label_);

            // Exit code:
            if (success_label_.is_linked()) {
                // Save captures when successful.
                __ bind(&success_label_);
                if (num_saved_registers_ > 0) {
                    // copy captures to output
                    __ LoadP(r4, MemOperand(frame_pointer(), kInputStart));
                    __ LoadP(r3, MemOperand(frame_pointer(), kRegisterOutput));
                    __ LoadP(r5, MemOperand(frame_pointer(), kStartIndex));
                    __ sub(r4, end_of_input_address(), r4);
                    // r4 is length of input in bytes.
                    if (mode_ == UC16) {
                        __ ShiftRightImm(r4, r4, Operand(1));
                    }
                    // r4 is length of input in characters.
                    __ add(r4, r4, r5);
                    // r4 is length of string in characters.

                    DCHECK_EQ(0, num_saved_registers_ % 2);
                    // Always an even number of capture registers. This allows us to
                    // unroll the loop once to add an operation between a load of a register
                    // and the following use of that register.
                    for (int i = 0; i < num_saved_registers_; i += 2) {
                        __ LoadP(r5, register_location(i), r0);
                        __ LoadP(r6, register_location(i + 1), r0);
                        if (i == 0 && global_with_zero_length_check()) {
                            // Keep capture start in r25 for the zero-length check later.
                            __ mr(r25, r5);
                        }
                        if (mode_ == UC16) {
                            __ ShiftRightArithImm(r5, r5, 1);
                            __ add(r5, r4, r5);
                            __ ShiftRightArithImm(r6, r6, 1);
                            __ add(r6, r4, r6);
                        } else {
                            __ add(r5, r4, r5);
                            __ add(r6, r4, r6);
                        }
                        __ stw(r5, MemOperand(r3));
                        __ addi(r3, r3, Operand(kIntSize));
                        __ stw(r6, MemOperand(r3));
                        __ addi(r3, r3, Operand(kIntSize));
                    }
                }

                if (global()) {
                    // Restart matching if the regular expression is flagged as global.
                    __ LoadP(r3, MemOperand(frame_pointer(), kSuccessfulCaptures));
                    __ LoadP(r4, MemOperand(frame_pointer(), kNumOutputRegisters));
                    __ LoadP(r5, MemOperand(frame_pointer(), kRegisterOutput));
                    // Increment success counter.
                    __ addi(r3, r3, Operand(1));
                    __ StoreP(r3, MemOperand(frame_pointer(), kSuccessfulCaptures));
                    // Capture results have been stored, so the number of remaining global
                    // output registers is reduced by the number of stored captures.
                    __ subi(r4, r4, Operand(num_saved_registers_));
                    // Check whether we have enough room for another set of capture results.
                    __ cmpi(r4, Operand(num_saved_registers_));
                    __ blt(&return_r3);

                    __ StoreP(r4, MemOperand(frame_pointer(), kNumOutputRegisters));
                    // Advance the location for output.
                    __ addi(r5, r5, Operand(num_saved_registers_ * kIntSize));
                    __ StoreP(r5, MemOperand(frame_pointer(), kRegisterOutput));

                    // Prepare r3 to initialize registers with its value in the next run.
                    __ LoadP(r3, MemOperand(frame_pointer(), kStringStartMinusOne));

                    if (global_with_zero_length_check()) {
                        // Special case for zero-length matches.
                        // r25: capture start index
                        __ cmp(current_input_offset(), r25);
                        // Not a zero-length match, restart.
                        __ bne(&load_char_start_regexp);
                        // Offset from the end is zero if we already reached the end.
                        __ cmpi(current_input_offset(), Operand::Zero());
                        __ beq(&exit_label_);
                        // Advance current position after a zero-length match.
                        Label advance;
                        __ bind(&advance);
                        __ addi(current_input_offset(), current_input_offset(),
                            Operand((mode_ == UC16) ? 2 : 1));
                        if (global_unicode())
                            CheckNotInSurrogatePair(0, &advance);
                    }

                    __ b(&load_char_start_regexp);
                } else {
                    __ li(r3, Operand(SUCCESS));
                }
            }

            // Exit and return r3
            __ bind(&exit_label_);
            if (global()) {
                __ LoadP(r3, MemOperand(frame_pointer(), kSuccessfulCaptures));
            }

            __ bind(&return_r3);
            // Skip sp past regexp registers and local variables..
            __ mr(sp, frame_pointer());
            // Restore registers r25..r31 and return (restoring lr to pc).
            __ MultiPop(registers_to_retain);
            __ pop(r0);
            __ mtlr(r0);
            __ blr();

            // Backtrack code (branch target for conditional backtracks).
            if (backtrack_label_.is_linked()) {
                __ bind(&backtrack_label_);
                Backtrack();
            }

            Label exit_with_exception;

            // Preempt-code
            if (check_preempt_label_.is_linked()) {
                SafeCallTarget(&check_preempt_label_);

                CallCheckStackGuardState(r3);
                __ cmpi(r3, Operand::Zero());
                // If returning non-zero, we should end execution with the given
                // result as return value.
                __ bne(&return_r3);

                // String might have moved: Reload end of string from frame.
                __ LoadP(end_of_input_address(), MemOperand(frame_pointer(), kInputEnd));
                SafeReturn();
            }

            // Backtrack stack overflow code.
            if (stack_overflow_label_.is_linked()) {
                SafeCallTarget(&stack_overflow_label_);

                // Call GrowStack(backtrack_stackpointer(), &stack_base)
                static const int num_arguments = 3;
                __ PrepareCallCFunction(num_arguments, r3);
                __ mr(r3, backtrack_stackpointer());
                __ addi(r4, frame_pointer(), Operand(kStackHighEnd));
                __ mov(r5, Operand(ExternalReference::isolate_address(isolate())));
                ExternalReference grow_stack = ExternalReference::re_grow_stack(isolate());
                __ CallCFunction(grow_stack, num_arguments);
                // If return nullptr, we have failed to grow the stack, and
                // must exit with a stack-overflow exception.
                __ cmpi(r3, Operand::Zero());
                __ beq(&exit_with_exception);
                // Otherwise use return value as new stack pointer.
                __ mr(backtrack_stackpointer(), r3);
                // Restore saved registers and continue.
                SafeReturn();
            }

            if (exit_with_exception.is_linked()) {
                // If any of the code above needed to exit with an exception.
                __ bind(&exit_with_exception);
                // Exit with Result EXCEPTION(-1) to signal thrown exception.
                __ li(r3, Operand(EXCEPTION));
                __ b(&return_r3);
            }
        }

        CodeDesc code_desc;
        masm_->GetCode(isolate(), &code_desc);
        Handle<Code> code = isolate()->factory()->NewCode(code_desc, Code::REGEXP,
            masm_->CodeObject());
        PROFILE(masm_->isolate(),
            RegExpCodeCreateEvent(AbstractCode::cast(*code), *source));
        return Handle<HeapObject>::cast(code);
    }

    void RegExpMacroAssemblerPPC::GoTo(Label* to) { BranchOrBacktrack(al, to); }

    void RegExpMacroAssemblerPPC::IfRegisterGE(int reg, int comparand,
        Label* if_ge)
    {
        __ LoadP(r3, register_location(reg), r0);
        __ Cmpi(r3, Operand(comparand), r0);
        BranchOrBacktrack(ge, if_ge);
    }

    void RegExpMacroAssemblerPPC::IfRegisterLT(int reg, int comparand,
        Label* if_lt)
    {
        __ LoadP(r3, register_location(reg), r0);
        __ Cmpi(r3, Operand(comparand), r0);
        BranchOrBacktrack(lt, if_lt);
    }

    void RegExpMacroAssemblerPPC::IfRegisterEqPos(int reg, Label* if_eq)
    {
        __ LoadP(r3, register_location(reg), r0);
        __ cmp(r3, current_input_offset());
        BranchOrBacktrack(eq, if_eq);
    }

    RegExpMacroAssembler::IrregexpImplementation
    RegExpMacroAssemblerPPC::Implementation()
    {
        return kPPCImplementation;
    }

    void RegExpMacroAssemblerPPC::LoadCurrentCharacter(int cp_offset,
        Label* on_end_of_input,
        bool check_bounds,
        int characters)
    {
        DCHECK(cp_offset < (1 << 30)); // Be sane! (And ensure negation works)
        if (check_bounds) {
            if (cp_offset >= 0) {
                CheckPosition(cp_offset + characters - 1, on_end_of_input);
            } else {
                CheckPosition(cp_offset, on_end_of_input);
            }
        }
        LoadCurrentCharacterUnchecked(cp_offset, characters);
    }

    void RegExpMacroAssemblerPPC::PopCurrentPosition()
    {
        Pop(current_input_offset());
    }

    void RegExpMacroAssemblerPPC::PopRegister(int register_index)
    {
        Pop(r3);
        __ StoreP(r3, register_location(register_index), r0);
    }

    void RegExpMacroAssemblerPPC::PushBacktrack(Label* label)
    {
        __ mov_label_offset(r3, label);
        Push(r3);
        CheckStackLimit();
    }

    void RegExpMacroAssemblerPPC::PushCurrentPosition()
    {
        Push(current_input_offset());
    }

    void RegExpMacroAssemblerPPC::PushRegister(int register_index,
        StackCheckFlag check_stack_limit)
    {
        __ LoadP(r3, register_location(register_index), r0);
        Push(r3);
        if (check_stack_limit)
            CheckStackLimit();
    }

    void RegExpMacroAssemblerPPC::ReadCurrentPositionFromRegister(int reg)
    {
        __ LoadP(current_input_offset(), register_location(reg), r0);
    }

    void RegExpMacroAssemblerPPC::ReadStackPointerFromRegister(int reg)
    {
        __ LoadP(backtrack_stackpointer(), register_location(reg), r0);
        __ LoadP(r3, MemOperand(frame_pointer(), kStackHighEnd));
        __ add(backtrack_stackpointer(), backtrack_stackpointer(), r3);
    }

    void RegExpMacroAssemblerPPC::SetCurrentPositionFromEnd(int by)
    {
        Label after_position;
        __ Cmpi(current_input_offset(), Operand(-by * char_size()), r0);
        __ bge(&after_position);
        __ mov(current_input_offset(), Operand(-by * char_size()));
        // On RegExp code entry (where this operation is used), the character before
        // the current position is expected to be already loaded.
        // We have advanced the position, so it's safe to read backwards.
        LoadCurrentCharacterUnchecked(-1, 1);
        __ bind(&after_position);
    }

    void RegExpMacroAssemblerPPC::SetRegister(int register_index, int to)
    {
        DCHECK(register_index >= num_saved_registers_); // Reserved for positions!
        __ mov(r3, Operand(to));
        __ StoreP(r3, register_location(register_index), r0);
    }

    bool RegExpMacroAssemblerPPC::Succeed()
    {
        __ b(&success_label_);
        return global();
    }

    void RegExpMacroAssemblerPPC::WriteCurrentPositionToRegister(int reg,
        int cp_offset)
    {
        if (cp_offset == 0) {
            __ StoreP(current_input_offset(), register_location(reg), r0);
        } else {
            __ mov(r0, Operand(cp_offset * char_size()));
            __ add(r3, current_input_offset(), r0);
            __ StoreP(r3, register_location(reg), r0);
        }
    }

    void RegExpMacroAssemblerPPC::ClearRegisters(int reg_from, int reg_to)
    {
        DCHECK(reg_from <= reg_to);
        __ LoadP(r3, MemOperand(frame_pointer(), kStringStartMinusOne));
        for (int reg = reg_from; reg <= reg_to; reg++) {
            __ StoreP(r3, register_location(reg), r0);
        }
    }

    void RegExpMacroAssemblerPPC::WriteStackPointerToRegister(int reg)
    {
        __ LoadP(r4, MemOperand(frame_pointer(), kStackHighEnd));
        __ sub(r3, backtrack_stackpointer(), r4);
        __ StoreP(r3, register_location(reg), r0);
    }

    // Private methods:

    void RegExpMacroAssemblerPPC::CallCheckStackGuardState(Register scratch)
    {
        DCHECK(!isolate()->IsGeneratingEmbeddedBuiltins());
        DCHECK(!masm_->options().isolate_independent_code);

        int frame_alignment = masm_->ActivationFrameAlignment();
        int stack_space = kNumRequiredStackFrameSlots;
        int stack_passed_arguments = 1; // space for return address pointer

        // The following stack manipulation logic is similar to
        // PrepareCallCFunction.  However, we need an extra slot on the
        // stack to house the return address parameter.
        if (frame_alignment > kPointerSize) {
            // Make stack end at alignment and make room for stack arguments
            // -- preserving original value of sp.
            __ mr(scratch, sp);
            __ addi(sp, sp, Operand(-(stack_passed_arguments + 1) * kPointerSize));
            DCHECK(base::bits::IsPowerOfTwo(frame_alignment));
            __ ClearRightImm(sp, sp, Operand(WhichPowerOf2(frame_alignment)));
            __ StoreP(scratch, MemOperand(sp, stack_passed_arguments * kPointerSize));
        } else {
            // Make room for stack arguments
            stack_space += stack_passed_arguments;
        }

        // Allocate frame with required slots to make ABI work.
        __ li(r0, Operand::Zero());
        __ StorePU(r0, MemOperand(sp, -stack_space * kPointerSize));

        // RegExp code frame pointer.
        __ mr(r5, frame_pointer());
        // Code of self.
        __ mov(r4, Operand(masm_->CodeObject()));
        // r3 will point to the return address, placed by DirectCEntry.
        __ addi(r3, sp, Operand(kStackFrameExtraParamSlot * kPointerSize));

        ExternalReference stack_guard_check = ExternalReference::re_check_stack_guard_state(isolate());
        __ mov(ip, Operand(stack_guard_check));

        if (FLAG_embedded_builtins) {
            EmbeddedData d = EmbeddedData::FromBlob();
            CHECK(Builtins::IsIsolateIndependent(Builtins::kDirectCEntry));
            Address entry = d.InstructionStartOfBuiltin(Builtins::kDirectCEntry);
            __ mov(r0, Operand(entry, RelocInfo::OFF_HEAP_TARGET));
        } else {
            // TODO(v8:8519): Remove this once embedded builtins are on unconditionally.
            Handle<Code> code = BUILTIN_CODE(isolate(), DirectCEntry);
            __ mov(r0, Operand(reinterpret_cast<intptr_t>(code.location()), RelocInfo::CODE_TARGET));
        }
        __ Call(r0);

        // Restore the stack pointer
        stack_space = kNumRequiredStackFrameSlots + stack_passed_arguments;
        if (frame_alignment > kPointerSize) {
            __ LoadP(sp, MemOperand(sp, stack_space * kPointerSize));
        } else {
            __ addi(sp, sp, Operand(stack_space * kPointerSize));
        }

        __ mov(code_pointer(), Operand(masm_->CodeObject()));
    }

    // Helper function for reading a value out of a stack frame.
    template <typename T>
    static T& frame_entry(Address re_frame, int frame_offset)
    {
        return reinterpret_cast<T&>(Memory<int32_t>(re_frame + frame_offset));
    }

    template <typename T>
    static T* frame_entry_address(Address re_frame, int frame_offset)
    {
        return reinterpret_cast<T*>(re_frame + frame_offset);
    }

    int RegExpMacroAssemblerPPC::CheckStackGuardState(Address* return_address,
        Address raw_code,
        Address re_frame)
    {
        Code re_code = Code::cast(Object(raw_code));
        return NativeRegExpMacroAssembler::CheckStackGuardState(
            frame_entry<Isolate*>(re_frame, kIsolate),
            frame_entry<intptr_t>(re_frame, kStartIndex),
            frame_entry<intptr_t>(re_frame, kDirectCall) == 1, return_address,
            re_code, frame_entry_address<Address>(re_frame, kInputString),
            frame_entry_address<const byte*>(re_frame, kInputStart),
            frame_entry_address<const byte*>(re_frame, kInputEnd));
    }

    MemOperand RegExpMacroAssemblerPPC::register_location(int register_index)
    {
        DCHECK(register_index < (1 << 30));
        if (num_registers_ <= register_index) {
            num_registers_ = register_index + 1;
        }
        return MemOperand(frame_pointer(),
            kRegisterZero - register_index * kPointerSize);
    }

    void RegExpMacroAssemblerPPC::CheckPosition(int cp_offset,
        Label* on_outside_input)
    {
        if (cp_offset >= 0) {
            __ Cmpi(current_input_offset(), Operand(-cp_offset * char_size()), r0);
            BranchOrBacktrack(ge, on_outside_input);
        } else {
            __ LoadP(r4, MemOperand(frame_pointer(), kStringStartMinusOne));
            __ addi(r3, current_input_offset(), Operand(cp_offset * char_size()));
            __ cmp(r3, r4);
            BranchOrBacktrack(le, on_outside_input);
        }
    }

    void RegExpMacroAssemblerPPC::BranchOrBacktrack(Condition condition, Label* to,
        CRegister cr)
    {
        if (condition == al) { // Unconditional.
            if (to == nullptr) {
                Backtrack();
                return;
            }
            __ b(to);
            return;
        }
        if (to == nullptr) {
            __ b(condition, &backtrack_label_, cr);
            return;
        }
        __ b(condition, to, cr);
    }

    void RegExpMacroAssemblerPPC::SafeCall(Label* to, Condition cond,
        CRegister cr)
    {
        __ b(cond, to, cr, SetLK);
    }

    void RegExpMacroAssemblerPPC::SafeReturn()
    {
        __ pop(r0);
        __ mov(ip, Operand(masm_->CodeObject()));
        __ add(r0, r0, ip);
        __ mtlr(r0);
        __ blr();
    }

    void RegExpMacroAssemblerPPC::SafeCallTarget(Label* name)
    {
        __ bind(name);
        __ mflr(r0);
        __ mov(ip, Operand(masm_->CodeObject()));
        __ sub(r0, r0, ip);
        __ push(r0);
    }

    void RegExpMacroAssemblerPPC::Push(Register source)
    {
        DCHECK(source != backtrack_stackpointer());
        __ StorePU(source, MemOperand(backtrack_stackpointer(), -kPointerSize));
    }

    void RegExpMacroAssemblerPPC::Pop(Register target)
    {
        DCHECK(target != backtrack_stackpointer());
        __ LoadP(target, MemOperand(backtrack_stackpointer()));
        __ addi(backtrack_stackpointer(), backtrack_stackpointer(),
            Operand(kPointerSize));
    }

    void RegExpMacroAssemblerPPC::CheckPreemption()
    {
        // Check for preemption.
        ExternalReference stack_limit = ExternalReference::address_of_stack_limit(isolate());
        __ mov(r3, Operand(stack_limit));
        __ LoadP(r3, MemOperand(r3));
        __ cmpl(sp, r3);
        SafeCall(&check_preempt_label_, le);
    }

    void RegExpMacroAssemblerPPC::CheckStackLimit()
    {
        ExternalReference stack_limit = ExternalReference::address_of_regexp_stack_limit(isolate());
        __ mov(r3, Operand(stack_limit));
        __ LoadP(r3, MemOperand(r3));
        __ cmpl(backtrack_stackpointer(), r3);
        SafeCall(&stack_overflow_label_, le);
    }

    void RegExpMacroAssemblerPPC::LoadCurrentCharacterUnchecked(int cp_offset,
        int characters)
    {
        Register offset = current_input_offset();
        if (cp_offset != 0) {
            // r25 is not being used to store the capture start index at this point.
            if (is_int16(cp_offset * char_size())) {
                __ addi(r25, current_input_offset(), Operand(cp_offset * char_size()));
            } else {
                __ mov(r25, Operand(cp_offset * char_size()));
                __ add(r25, r25, current_input_offset());
            }
            offset = r25;
        }
        // The lwz, stw, lhz, sth instructions can do unaligned accesses, if the CPU
        // and the operating system running on the target allow it.
        // We assume we don't want to do unaligned loads on PPC, so this function
        // must only be used to load a single character at a time.

        __ add(current_character(), end_of_input_address(), offset);
#if V8_TARGET_LITTLE_ENDIAN
        if (mode_ == LATIN1) {
            if (characters == 4) {
                __ lwz(current_character(), MemOperand(current_character()));
            } else if (characters == 2) {
                __ lhz(current_character(), MemOperand(current_character()));
            } else {
                DCHECK_EQ(1, characters);
                __ lbz(current_character(), MemOperand(current_character()));
            }
        } else {
            DCHECK(mode_ == UC16);
            if (characters == 2) {
                __ lwz(current_character(), MemOperand(current_character()));
            } else {
                DCHECK_EQ(1, characters);
                __ lhz(current_character(), MemOperand(current_character()));
            }
        }
#else
        if (mode_ == LATIN1) {
            if (characters == 4) {
                __ lwbrx(current_character(), MemOperand(r0, current_character()));
            } else if (characters == 2) {
                __ lhbrx(current_character(), MemOperand(r0, current_character()));
            } else {
                DCHECK_EQ(1, characters);
                __ lbz(current_character(), MemOperand(current_character()));
            }
        } else {
            DCHECK(mode_ == UC16);
            if (characters == 2) {
                __ lwz(current_character(), MemOperand(current_character()));
                __ rlwinm(current_character(), current_character(), 16, 0, 31);
            } else {
                DCHECK_EQ(1, characters);
                __ lhz(current_character(), MemOperand(current_character()));
            }
        }
#endif
    }

#undef __

} // namespace internal
} // namespace v8

#endif // V8_TARGET_ARCH_PPC
